The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to perform deposition and/or etching of film on a substrate such as a semiconductor wafer. The substrate processing systems typically include a processing chamber with a substrate support such as a pedestal, an electrostatic chuck, a plate, etc. A substrate such as a semiconductor wafer may be arranged on the substrate support. In chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), atomic layer deposition (ALD) or PEALD processes, a gas mixture including one or more precursors may be introduced into the processing chamber to deposit or etch a film on the substrate. Plasma may be used to activate chemical reactions.
Some processes use a gas distribution device such as a showerhead. The gas distribution device may include a faceplate with a plurality of gas through holes. The gas through holes are arranged in a pattern to provide a desired gas flow pattern. Process gases are supplied to a cavity in the gas distribution device and are disbursed by the through holes of the faceplate over the substrate.
In PECVD and PEALD processes, radio frequency (RF) plasma may be used to activate chemical reactions. For example, a capacitively coupled plasma (CCP) generator may be used to generate plasma in the processing chamber. The plasma is struck in a space between the faceplate of the gas distribution device and the pedestal. In other words, the faceplate of the gas distribution device may act as one electrode of the CCP generator.
Current gas distribution plates are primarily made of aluminum if the plates serve as the electrode. For high temperature applications (greater than 400° C.), aluminum is not used for the gas distribution plate or the electrode due to the lower melting temperature of aluminum. In addition, some gas chemistries that are used in PECVD and PEALD processes are not compatible with aluminum.
Ceramic plates may also be used as gas distribution devices. While addressing the issue of temperature and chemical compatibility, the ceramic plates generally cannot be used in CCP circuits. In order to function as an electrode, a metal element is embedded in the ceramic plate. Embedding a metal electrode in a ceramic body (like a pedestal or chuck) has been accomplished using a hot press (or sintering) manufacturing process. However, the hot press manufacturing process requires a significant amount of machining and grinding to be done after the ceramic faceplate is sintered. The post-sintering grinding is both expensive and time consuming due to the hardness of the ceramic plate. Therefore, it is cost prohibitive to include even a small number of through holes for gas distribution in ceramic plates manufactured using the hot press manufacturing process.
The hot press manufacturing process also places significant limitations on the dimensional accuracy of embedding the metal electrode in the ceramic plate. In other words, the precision in setting the horizontal and vertical location and/or the planarity of the electrode is limited due to the hot press manufacturing process. This limitation makes it difficult to accurately grind through holes while avoiding the metal electrode. These issues make the hot press manufacturing process economically unfeasible when producing ceramic gas distribution plates with embedded electrodes.